


Catch and Release

by Slenbee, SuccubusKayko



Series: Frostiron Oneshots [5]
Category: Iron Man (Movies), Marvel Cinematic Universe, The Avengers (Marvel Movies), Thor (Movies)
Genre: Alternate Universe - Deep Sea Research Base, Deep Sea AU, Deep Sea Researcher Tony, Fluff and Smut, Inspired by Roleplay/Roleplay Adaptation, Intersex Loki (Marvel), Knotting, M/M, Mention of oviposition, Mer loki, MerMay, Not Canon Compliant, Porn With Plot, Porn with Feelings, Teratophilia, Tooth-Rotting Fluff, Water Sex, Wordcount: 5.000-10.000, Xenophilia, mention of MPREG, weird dicks
Language: English
Status: Completed
Published: 2020-05-25
Updated: 2020-05-25
Packaged: 2021-03-03 00:14:45
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 8,074
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/24375622
Author URL: https://archiveofourown.org/users/Slenbee/pseuds/Slenbee, https://archiveofourown.org/users/SuccubusKayko/pseuds/SuccubusKayko
Summary: Tony returns to base after a six month lecture tour with Jane and Thor. He's finally made up his mind about a very important matter and he can't wait to tell his lover.
Relationships: Loki/Tony Stark
Series: Frostiron Oneshots [5]
Series URL: https://archiveofourown.org/series/1841824
Comments: 27
Kudos: 242





	Catch and Release

**Author's Note:**

> This is Slenbee and I's contribution to MerMay this year~! <3
> 
> We hope that you love and adore it as much as we enjoyed writing it. <3

Tony couldn't have kept the grin off of his face if he tried as he climbed into the suit and flipped the switch that sealed him in. He methodically went through his mental checklist to get the suit pressurized and ready for departure, even though he could follow the procedures with his eyes closed. He knew that it would take approximately four hours to get down to the base with stops at each of the depressurization points, and that it would take another hour to re-pressurize once he was inside. Another three hours to get signed in, settled into his cabin, and debrief with his colleagues. So, all in all, a good seven-ish hours until he was free to roam the deep-sea base.   
  
More importantly, however, was that he would get to see  _ Loki _ before nightfall.   
  
"Alright, Rhodey, sending you the readings, then I'm ready to dive," Tony called over communications as he input coordinates and readjusted his seat, "Let's get this show on the road."   
  
"I know you're in a hurry, man, but take a chill pill, would you," Colonel Rhodes voice crackled over the radio, "Loki's not going anywhere. If he hasn't found a better fish down there by now, then he's not going to."   
  
"Platypus, there  _ is _ no better fish in the sea," Tony purred, his cheeks aching from grinning so hard.   
  
"You're damned right," James chuckled as the suit rumbled and slowly descended into the waves, "Clear for departure, buddy. Don't do anything I wouldn't do."   
  
"If I didn't do anything that  _ you _ wouldn't do, I wouldn't be down here, Rhodes."   
  
"Go to hell, Stark. Have fun!"   
  
The radio switched off with a squeal of static and a click, then Tony was dropping below the waves, the view-ports slowly filling with bright, verdant blue and a rush of bubbles to the surface. He pulled one of his earbuds out of the rucksack at his side and placed it in his ear, his voice sweet and crooning as he said, "Hey, baby. I'm coming home.”

Loki could not remember the last time he felt such joy in hearing another's voice. It was like a breath of fresh water to him. The spear that landed him a fish he had been hunting for hours, the pearl so perfectly sized for one of his projects. There were so many ways he could try and compare Tony's voice to other things that brought him joy.

But in the end?  _ Nothing _ in this ocean made him happier.   
  
"I am no 'baby', my dear mortal. You know this." The Mer replied with a hushed yet amused voice, his tail and fins fluttering as he continued his exploration of a distant sea wreck. Tugging and pulling a set of rotten boards away, he slipped inside the hull and into the hold. With a croon of excitement he made a beeline towards a half buried bottle that still seemed intact. "Yet even still I find myself capable of childlike wonder. I've found a gift for your collection. Would you like to see?"   
  
Lifting a webbed hand, the Mer touched the device in his ear, a tiny reader popping out of the side that cast it in a thin blue line that scanned his nearby surroundings. When it fluttered over the bottle, it highlighted the worn etching and sent the data back to Tony's HUD.   
  
"What year do you think it is?"

"It'll be easier to tell in person, but judging by the type of glass and the font? Maybe mid 1800s," Tony replied, gaze flickering back and forth between the projection and the way-finder in his HUD, the smile evident in the warmth of his voice, "Does it have wax over the cork?"

Tony chattered and babbled with Loki throughout the trip, pausing only when he had to re-stabilize the suit and adjust for the change in pressure. He let out a long, breathy sigh as he neared the final checkpoint, his voice almost hoarse as he said, "Alright, Lokes. Gotta go radio silent now. I'll see you in a couple more hours. Meet me at Bezzy's tank? I wanna check her out before we settle in for the night and we both know I won't if I go to the cabin first."

With the bottle and all of his other goodies safely tucked into the bag he carried at his side, the young Prince smiled and made his way back to base. It would take him just as long to finish the journey, but thankfully chatting with his beloved mortal helped speed things along. "I shall see you then. The last I visited, her pregnancy was going along quite swimmingly. I am sure she will be most delighted to see you."   
  
Making a few pit stops at a couple volcanic vents, Loki gathered up a dozen or two mineral samples and headed back home. The trip took far less time than he previously thought, and thus with what was left, he readied his little 'treasury' and prepared the rest of the items for the scientists to examine.   
  
Loki was practically beaming when he felt Tony's presence grow closer, his fins fanned out and all aflutter when the elevator containing him finally made its last descent. He circled it all the way down, smiling and touching at the glass path ways whenever he could.   
  
Disappearing into the narrow pathways, he surfaced at the private pool the divers used to enter and exit Bezzy's tank, a wide smirk set about his cheeks as he tried to contain his excitement. "Hello Anthony.~"

Tony's cheeks split into a bright smile, his deep brown eyes sparkling with happiness as he waddled his way over to the diving pool. The flippers on his feet slapped comically against the ground, but Tony couldn't give a damn how incredibly ridiculous he looked in his wet-suit at that moment. He was back on base. He was back with his  _ lover _ and wouldn't be leaving again for another six months.   
  
Nothing in the world could have torn him away at that moment.   
  
A low, burbling rumble bubbled up from the pool and Tony couldn't help but snigger as he glanced up at the view-port to see one of Bezzy's big black eyes peering back at him.   
  
"Yeah, I missed you, too, Bezz. Gimme a minute to say ‘hi’ to my guy, would you," Tony chuckled at the chastised sounding groan he received in reply as he plopped down at the edge of the pool and made grabby hands at Loki, "C'mere, quick, before she riots."

Grabbing hold of the tank edge Loki pulled himself up and out onto the diving ladder platform, his smile never fading. Grabbing the respirator vest that Tony had made for him he clicks it into place, a sigh of content mingling with a croon whilst Tony approached and the vest cycled freshwater into his lungs.   
  
Extending his arms toward his mortal companion the webbing between his fingers receded much like the sharp nails on his fingers. Allowing the two to lace fingers without the worry of accidentally cutting or harming his fleshy companion. "I missed you." Loki said with a purr, the human's hands brought to his face so that he could kiss and nuzzle against them.   
  
"How have things been on land? Is my brother behaving?" Thor had given up his tail to live with the humans, to fall in love and live his life protecting this world. Loki got to see him on occasion, but even  _ he _ found this vast ocean to be lonely sometimes. Especially when he was forced to wait for his own beloved mortal to finally return.   
  
He might not see the above world any time soon, but for now? He had Anthony and the other humans to keep him company. A fact he wouldn't trade for anything in his wildest dreams.

"He's being good, yeah," Tony chuckled, gently tracing his fingers over the lines of Loki's face, his eyes darting about to look his lover over, "He keeps breaking Jane's toaster, but I'm working on that."   
  
Tony smiled warmly at his companion and cupped his cheeks in his calloused fingers, drawing him closer, "Now c'mere and give me a kiss, gorgeous. Let's give ol' Bezz a show." He winked playfully at Loki, then leaned up to press his lips to Loki's, warm meeting cool, but no less pleasant.

Loki melted into that kiss, cool lips warming instantly beneath the touch of his lover's own. Wrapping his arms around Tony's neck the Mer draws him in closer, almost teetering on the edge of falling back into the water, but not quite. When he grew lightheaded he finally pulled back with a smile, tail swishing to and fro in a sign of pure happiness. "By the nine, how I've missed you."   
  
Resting their foreheads together, he closed his eyes, a shimmer of color cascading along his form. It brightened up his fins and the various bands of color that covered him, his fins even flaring out in a gorgeous display.

"And I missed you," Tony hummed, peppering the Mer's cheeks with quick little pecks. He reluctantly pulled away with a tired sigh and glanced back over his shoulder at Bezzy's eye still on them in the view-port, "Alright, girl. Your turn for some attention."   
  
He gave Loki's waist a quick squeeze, only the briefest of hugs, and rolled his eyes, "Just got here and she's already working me to the bone. Can you believe this shit?" He was teasing, of course, his lips curling into a wry smile as he looked over his lover wistfully and strapped an air tank to his vest.   
  
"I'm warning you now, woman, if you keep me for too long, I'm going to be  _ very _ upset," Tony grumbled playfully as he slipped into the pool and held the respirator over his mouth, "And I'll make sure Loki doesn't share  _ any _ of the sweets I brought back with me."   
  
He gave his lover a quick wink, pulled down his diving goggles, slipped the respirator into his mouth, and disappeared below the rippling surface of the pool.

After preening under all of that attention the Mer was left to slide back into the water with a splash. Removing the vest, he replaced it onto the hook from where it had been stationed, eagerly awaiting his mortal companion to join him once he had finished getting ready.   
  
Loki stayed quiet while Tony worked, keeping his distance while also staying close enough to help whenever needed. Several hours passed as the two moved from tank to tank, checking in on the resident wildlife that Loki had brought in for rehabilitation.   
  
Be it an extinct species or an unknown one, the Mer had done a lot of work since he and Tony's fate had been intertwined. After being nursed back to health by none other than the Philanthropist himself, he and Loki had grown close during their time together. So much so that they had come to call each other  _ lovers. _ Much like his brother, he seemed destined to follow a similar fate, however as of right now.. He seemed to have no intentions on giving up his tail.   
  
"I have things waiting for you in the cabin." Loki piped up as the two of them finished up their final inspection. "I've been busy these past couple months while you were away. So I hope that you find these new trinkets enjoyable."

"I can't wait," Tony's smile was warm as he leaned down to steal a quick kiss. "I'll meet you upstairs in a few minutes," he said as he pulled himself out of the diving pool and slipped the tank off of his back.   
  


It took him about ten minutes to slip out of his wetsuit and set the air tank up to refill, then another twenty to make his way up to his cabin and get the tank water rinsed off of him. Regardless of the fact that Loki didn't seem to mind the 'cross contamination', Tony felt better when he didn't have to risk it. Sure, Loki was plenty healthy now, but he'd been in rough shape when they first met. It had taken a  _ long _ time for Tony to even feel comfortable letting Loki out of his quarantine tank to begin with.   
  
"Never can be too careful," he murmured to himself, a slight frown on his lips as he descended the stairs to the lounge of his private cabin. He brightened quickly when he spotted Loki waiting for him in their living area, however.   
  
The crystal clear pool that made up the majority of the room was deep enough for Loki to live and breathe comfortably, but shallow enough for Tony to be able to stand and get around easily.   
  
He loosened the sash on his robe and let it fall open as he reached the edge, his smile widening to a lascivious grin as he let it fall to the ground. "Honey, I'm home," he teased as he stepped into the water, a shiver running up his spine and raising the hair on his body as the cool moisture licked at his skin. **  
** **  
** Loki moved like a black shadow beneath the crystal clear waters, the only hint of color showing when the light caught on his tail. Sliding away from the nest he had created the Mer made his way towards his beloved mortal, a smile of pure delight stretched across his cheeks. Once Tony had stepped into deep enough waters the Mer circled him and rose from the pool, cool fingers trailing up along the outside of cloth covered thighs. "Missed you." Loki said with a whisper, a kiss pressed to the warm lips that awaited him.   
  
"Come, let me show you what I found." Loki lifted a hand and rested it at the center of Tony's chest, a spider web of magic dancing out from beneath his palm. Wisps of green and gold traveled up and around to create a thin barrier that would protect his lover from drowning. Effectively allowing him to spend as much time as he desired beneath the waters that his aquatic lover called home. Taking Tony's hand into his own, Loki slowly pulled him under, carrying him off to his nest to show him the various odds and ends he had collected. The first of such being the corked bottle from before. **  
** **  
** "Ohhh," Tony warbled, turning the bottle over and over in his hands, "I think I was pretty close!" He grinned wide and stole a quick kiss, then eyed the bottle more critically, "Seal is still intact, too. Nice find, Lokes! Shit. Now I kind of want to go to the wreck you found this at..."   
  
He twisted his lips into a teasing, yet hopeful smile, eyes crinkled guiltily, "I guess that can wait, though. I promised you a week before I really dove back into work, didn't I?" He wet his lips despite not needing to, a habit he would never be able to break, especially when it sometimes caught Loki's attention so fantastically.   
  
He grinned sheepishly and paddled over to the soft bed of fresh kelp and seal leathers that Loki kept for them, crossed his legs in a mimicry of sitting, and motioned for Loki to come closer, "What else did you get, fancy-fins?"

"I found this down near one of the volcanic vents." Picking up a rather large, rough looking stone the Mer brought it over to his finless companion and curled around him. "I think it is from the sky. One of those.. what do you humans call them," Smiling sheepishly he let out a bubble of laughter, " _ 'Meat-eaters _ ?'"   
  
Depositing it into Tony's lap he reached under one of the pelts nearby and pulled out a large pearl. "I also found this, oh! And this too!" Grabbing at this and that he set them neatly in and on his tail and his lover's lap, finned hands coming together as he eagerly waited for him to appraise them all. "What do you think?"   
  
"I love them," Tony purred, though his eyes rarely left Loki throughout the show and tell session. He carefully lined the items in his lap around the little nest and arranged them just so, as Loki had explained was the custom of his people, then turned to Loki once more.   
  
He curled his arms around the Mer's lithe waist and pulled him closer, his lips pressing to the line where flesh met scale, the feel of smooth skin and rough, dermal plates sending a shiver down his spine and breaking goosebumps over his skin, "I think I like this one the best, though." He nipped at Loki's belly button, then trailed his tongue up his torso, mouth hot on his cool skin, a soft, affectionate growl vibrating through the water as he hugged his lover tight, "Fuck, I missed you."   
  
Dark lashes swept low, an affectionate purr rumbling past the Mer's chest when warm lips brushed against cool skin. Reaching down he pet a hand through Tony's hair, nails grazing his scalp before he soothed it with another stroke of his fingers. Breathing a sigh of content, Loki released a string of bubbles past his lips before letting his head fall back. "And I you, my darling little land walker~"   
  
Winding his tail a little tighter in the form of a hug, he let himself relax back against the pelts that lined his makeshift nest. "You've been gone so long. I thought I might never see you again." He knew better deep down that that was a  _ lie, _ but that still didn't make his heart ache any less now that he had Tony right where he wanted him.  _ Here. _   
  
Humming to himself he trailed his hands down Tony's sides, fingers teasing the edge of the swim trunks that Tony wore. "Did you think of me while you were away? There wasn't a day that passed that you weren't on my mind~" **  
** **  
** "Well, when you consider that your brother and his girlfriend follow me  _ most _ places that I go these days," Tony teased, shimmying his hips playfully, "And that I spend almost every waking moment talking about the research we do down here to an amphitheater full of people who only want to know about this gorgeous  _ piscis _ I know..." He feigned disinterest and frustration for a moment, dramatically throwing his arm over his eyes, "It's like they don't even  _ care _ about the ocean..."   
  
He lifted his arm to peek at his lover and couldn't keep the wide grin from his mouth as he sassed, "But, no, didn't think about you for a moment. I'm just  _ so busy _ , you know."   
  
Loki's fins flared with that feigned gasp, his expression dropping into one of surprise before it was gone a second later. With a smirk and a huff he grabbed at Tony's hips, easily maneuvering him onto his back so that the Mer could lay draped over him. "So busy, you say..." Dark hair moved around him like a pool of ink, finned ears twitching. Leaning in close he let their lips brush, voice lowering to a near whisper.   
  
"That's such a shame. And here I wanted to show you  _ just _ how much I missed you." Sliding down Tony's body, the Mer peppered his skin with kisses and gentle nips of his teeth, pausing here and there to suck in  _ all _ the right places _. _ "Would you like that?" Teasing his fingers along the waistband of Tony's shorts, he couldn’t help but purr. "For me to show you?" Kissing just shy of his lover's belly button he cast a look upward, tail swaying side to side like the cat who'd gotten the cream.   
  
Tony couldn't have kept up the ruse if he'd tried; he instantly melted beneath Loki's hands and mouth, relaxing against the bed of kelp and hides, a soft hum of content bubbling up from his chest.   
  
"Yes, please," he whispered breathlessly, a cascade of bubbles escaping his lips in a rush as Loki's fingers teased at the waistband of his shorts, "God, Lokes. Need you so bad..." He tilted his head back further, hips rising off of the ground encouragingly, "Please, babe. Missed you."   
  
Sharp teeth flashed dangerously close to Tony's belly button, the caress of his fingers creeping closer to the 'prize' he sought to claim as his own. Loki drew in a breath before letting it out slowly, the thin slits along his ribs fluttering. "I can smell you." He breathed, tongue unfurling to drag across warm skin. Lowering his head further he nuzzled against the side of Tony's growing arousal, trapped beneath his shorts, another sound of content leaving him.   
  
"May I taste you?" Sharp eyes flicked upward, movements stalling long enough so that he could get an answer.   
  
Tony's fingers slipped to gather a handful of Loki's inky locks, gently guiding him closer, " _ Fuck, yesssss _ ." He pulled his lower lip between his teeth and groaned loudly, helping his lover slip his trunks down enough for his cock to bob free.   
  
His thick prick rested heavily against his belly for a moment, leaking slick pearls that clouded the water with every hard twitch and flex, "Oh, gods, Loki. Fuck, I want you so bad."   
  
Loki took Tony's enthusiastic response with a wicked smirk and a devilish chuckle to match. "Such an eager thing you are." The Mer mused, a single, webbed hand snaking its way forward to curl about the mortal's aching arousal. Rather than take him into his mouth immediately, he nuzzled against Tony's cock, peppering it with kisses and the gentle brush of his lips.   
  
_ "Mmn~ Missed this. Missed  _ **_you._ ** _ " _ He breathed longingly, tongue darting across his lips before he opened his mouth and lapped a long, lazy trail from the base clear to the tip. Loki's tongue was far longer than any human’s, allowing him to partially curl it around the tip of Tony's cock. Lavishing it with slick saliva and a chill akin to the Mer's own body.   
  
Tony's breath hissed through his teeth at the initial sting of Loki's chill tongue, his cock twitching and softening for the briefest of moments, then throbbed tellingly as it got with the program. "Oh f _ uuu _ ck," he groaned intelligently, fingertips momentarily digging into the Mer's scalp, before he relaxed and scraped blunt nails through Loki's hair, "Christ, I've missed you..."   
  
He shivered and writhed beneath his lover's unfairly talented lips, slowly tensing, body curling in on itself as he neared his inevitable end, "Shit,  _ sweet-gills _ , I'm gonna...  **Fuck** , gonna cum..."   
  
Pulling his head back the Mer drew in that sinful tongue, cool water dancing across overheated skin when he let out a snicker. "I only just started and already you're fit to burst?  _ Tsk tsk. _ " Dragging his nails along Tony's thighs, he soothed the sting with the pads of his fingers, cheek nuzzling into the inside of his thigh. "And here I thought that  _ I _ was the greedy one."   
  
Flashing those sharp teeth Loki took Tony in hand, giving that thick cock of his a firm stroke or two before pulling away. Rising up he pressed their lips together in a firm kiss, the brush of something slick and  _ moving _ rubbing up against Tony's thigh.   
  
Tony could only groan like he was dying, half delirious with lust for his lover and bordering on desperate. He slipped a hand between them and loosely gripped Loki's slick length, winding it gently over his calloused fingers as he buried his free hand into the Mer's inky-dark locks to pull him in for a searing, claiming kiss.   
  
Even with the water flowing easily through his lungs like air, he was finding it hard to breath through the molten need burning through his veins. He pulled away with a heaving gasp, instead cradling Loki's head in the crook of his neck and shoulder. He let out breaths that shook him to the bone, opened and closed his mouth, words dying on his tongue before he could even give them clear thought. He stroked over Loki's writhing cock with perhaps more force and speed than necessary, but he could find no other way to convey his absolute  _ need _ for his lover.   
  
Six months without his piscine beau and Tony was a puddle of wretched, frenzied desire.   
  
Loki shuddered and moaned when those well worn fingers curled about his inhuman cock, holding him firm even as he twitched and thrashed within his grasp. Rolling his hips the Mer sought friction, any sort of relief to the bone deep need that roared through him.   
  
With a hand tugging him up Loki found his lips claimed by Tony's own, his all too sharp teeth finding his pulse a moment later when his head was lowered down to his neck.  _ "N-need... need to..." _ Growling low in his throat he reached between them, one hand shoving Tony's own away, the other hiking up one of his thighs to curl around his waist.   
  
It didn't take much for him to find Tony's hole, the tight furl teased and prodded until the slick tip of his prehensile cock wiggled its way inside.   
  
"Fffffffuuuuuuuh," Tony moaned, loud and long, as Loki slipped into him, his cock writhing and working its way all the deeper. Loki was  _ long _ to say the  _ least _ and Tony was always overcome with how  _ deep _ his lover could go after his trips away. As though he'd somehow forgotten how helplessly  _ filled _ he felt when Loki was sheathed fully.   
  
And then there was the way his cock  _ moved _ , as though it had a mind of it's own and was always seeking to drive Tony closer and closer to the edge of madness. Needless to say, Loki had ruined Tony for anyone else, though that was  _ long _ before they'd 'lain' together for the first time.   
  
Eyes squeezed tight and fingers fisted in his lover's hair, holding him tight to his body as though he couldn't possibly be close enough. Tony's lips parted on an almost miserable sounding cry, choked off and leaving him gasping desperately for air, though by the way he locked his feet behind Loki's back and held on all the tighter, it was clear that he was feeling  _ anything _ but pain or despair.   
  
Stars burst behind his eyelids as Loki's body danced with his own and all Tony could do was  _ breath and hold on _ . **  
** **  
** Hovering over his two legged lover the Mer indulged himself to the fullest. Relishing in the slow slide into the slick hole that clung to him, a single thrust of his hips burying him nearly to the hilt. Loki's cock was.. different, to say the least. Thin at the tip and much thicker at the base. Much like an aquatic mammal would be, save for the fleshy ridges that lined his length and the slight  _ bump _ that lay near the base. A hidden knot that would tie them together until Loki was thoroughly done ravaging him.   
  
Loki dug his nails into the pelts on either side of his companion as he fucked him full. Hips rocking and thrusting at a deep and brutal pace. Uttering a curse, the Prince closed his eyes and growled, forehead resting against Tony's shoulder whilst he desperately clung to him. His  _ teeth _ dangerously close to sinking into his skin.   
  
"Shi-," Tony choked as he tucked his head under Loki's chin and scrabbled for a better grip, blunt nails scraping at flesh and scale alike. He tossed his head and worried his lips between his teeth, drawing pinpricks of blood as he shook and trembled and writhed on the Mer's cock.   
  
Dizzy with pleasure, bordering on pain, Tony sank his teeth into the meat of Loki's chest and screamed. His cock twitched violently, seed spilling and clouding the water between them. His eyes rolled in their sockets and his lashes fluttered, his fingers forming a white knuckled grip and digging furrows into lithe muscle.   
  
His hips bucked, driving up into nothing as wave after wave of pleasure overtook him, his channel rhythmically clenching around the near alien, but all too familiar, prick inside of him.   
  
A sharp keen of bliss poured past Loki's lips when those teeth sank into his chest and those inner muscles clamped down on him. It took every ounce of strength that he had not to brutally grab at Tony's hips and dig his nails in. Instead he held himself in check, holding his hips firmly whilst fucking into his fluttering hole.   
  
The taste of blood and seed flooded his senses, sending him into a frenzy of desire and pure, unbridled  _ need. _ Gnashing his teeth the Mer hissed and groaned, hips growing messy in their movements as his own release threatened to pull him under.   
  
At the base of Loki's cock that bump began to swell, the pleasure in his belly pooling lower and lower. It was growing hard for him to keep up his thrusts, that knot catching at Tony's rim before he finally buried it inside. With a full body shudder, he finally came, fins flaring out around him, the magic beneath his skin causing him to glow. Loki sank his teeth into Tony's shoulder on instinct, a low growl muffled against his skin when he tried to pull away.   
  
Twitching and fluttering, his fins gradually relaxed, the weight of his body blanketing his mortal lover protectively. **  
** **  
** The thick knot at the base of Loki's cock was the final straw for Tony. As the knot swelled and stretched him to his limit, then finally sunk beyond the taut muscle of his rim, Tony's voice broke and his body went lax and limp.   
  
He swallowed reflexively around the mouthful of blood and spend and salt-rich water as it filtered through his magically enhanced lungs, just like air would burn through them after a marathon run. His body gently undulated with the current of the pool, held in place only by Loki's body curled tight around and inside of him. His lashes fluttered and his fingers twitched weakly against Loki's sides, his mouth lax and lips kiss-swollen and bruised.   
  
The first coupling after his return to base was always the most difficult for his aging body, but Tony wouldn't trade the bruises, aches, and pains for anything.   
  
Tony's lashes fluttered, glazed, brown eyes peeking hazily from below heavy lids. One corner of his mouth slowly curled up into the faintest of smiles as Loki anchored them down into their love nest with his claws and powerful fins. He dazedly watched as the dark furl of those fins danced in and out of his vision, swirling through the clouded water with only the barest of twitches from Loki's powerful muscles; watched as they glowed and sparkled and winked with an ethereal glow, the membranes near translucent in the overhead lights.   
  
"Beau-iful," Tony breathed, lips barely moving against the fluttering fins along the tips of Loki's ears, "So, beau-iful."   
  
Dark lashes fluttered open and closed, lust blown silver now ringed in  _ red. _ Loki's hips moved on their own, twitching forward with every thick release of seed that filled the willing body below. He knew not how much time had passed before he finally came to his senses. But when he did, the Mer was carefully removing his teeth from Tony's shoulder, lapping gently at the mark with his tongue before healing it with a magical kiss.   
  
Slender arms slid beneath the body below him, gathering Tony up and against him as he began to move. Carefully carrying his human over to the shallows they breached the surface at a second little nest the Mer had created. This one more fitting for his air breathing lover and his need for oxygen.   
  
Drawing in a shaky breath Loki nosed and nuzzled against Tony's neck and shoulder, crooning and purring his praise whilst a tender, affectionate smile tugged at his lips. "Are you well? I didn't bite too hard, did I?"   
  
"S'fine," Tony husked, resting heavily against his lover's side as he nuzzled his cheek against Loki's. He wet his lips and cleared his throat, took a deep breath of fresh, dry air and let out a long, drawn out groan of exhaustion. He lifted his head just enough to catch Loki's eyes, then let it fall back against the Mer's chest, "I'm gonna sleep  _ so _ good tonight..."   
  
His lips curled into a slightly deprecating smile, but his half-lidded eyes still sparkled with mirth and affection, "I missed this. Jane thinks I'm crazy, letting you get at me like this, but then I remind her that she picked the muscle head and that gets her blushing like you wouldn't believe."   
  
He snickered and scrunched his nose playfully, then pressed back against his lover, a soft whimper escaping his lips, voice hoarse as he murmured, "Her loss, honestly."   
  
Cool hands soothed over Tony's hips, the gentle brush of his lips feathering across the telltale mark where his teeth had once been. "Jane doesn't have to worry about  _ this, _ " Loki rolled his hips, a shuddering breath rushing past his lips at the pressure it put upon his pulsing cock. " _ Mmn~ _ Thor made his choice, just as I made mine." Leaning back, the Mer placed a tender kiss to Tony's lips. "Besides... I know you enjoy this just as much as I do. You... do enjoy this, right?"   
  
A worried look encompassed Loki's features, fins visibly drooping at the thought of Tony having grown to possibly dislike their coupling. "You would tell me if you were uncomfortable, yes? I would never wish to cause you harm..." Placing a hand over Tony's stomach the Mer let out a soft croon, the slight bulge that had begun to form from his release leaving him torn between bliss and worry.   
  
"Of course I enjoy it, babe," Tony comforted, wrapping his arms around Loki's neck and pulling him in for a long, gentle kiss. "I adore you, Lokes. And  _ of course _ I would say if you were  _ really _ hurting me." He pulled back just enough to touch his nose to Loki's, a salacious grin curling his lips, "More than I can handle, anyway."   
  
He curled his fingers around the back of Loki's neck and gently stroked the hinge of his jaw and the base of his finned ears with his thumbs, "You'd tell me if you got bored with your poor old mortal, right? If I wasn't fulfilling your needs?"   
  
Closing his eyes, Loki smiled and purred, leaning into his lover's touch as he massaged and rubbed in one of the places he loved the most. With a flutter of dark lashes, he eventually opened his eyes, head lowering so that their noses brushed once more. "You are my life-mate. I have claimed you as mine and left the signs to prove it. I can hardly imagine a time where I could possibly grow bored with you at my side."   
  
They shared plenty in common, not to mention the bonding moments they had shared. Loki had his mind made up already. There was no giving up Tony, nor was there any chance or plans on leaving him. A fact he held true to even now as they lay tied together. "I love you, I  _ adore _ you, my darling little mortal. My lovely little land walker~"   
  
"Love you, too, sweet-fins," Tony hummed as he wiggled and shivered, trying to get himself more comfortable and only managing to rile himself up again. He knew from experience that they would be locked together for a while yet, but that didn't mean they didn't still have a myriad of ways to drive each other wild.   
  
He huffed out a laugh at his train of thought, even as his body began to protest his position and Loki's not so gentle intrusion. He squirmed a bit more, trying to find a more comfortable angle for his hips, but only managed to grind Loki's slithering prick more harshly against his prostate.   
  
"Shit," he cursed breathlessly, eyes falling closed in equal parts discomfort and bliss. He bothered at his lower lip for a few moments, giving himself some time to reorient himself, then winced, "Need to get back in the water, babe. Back's starting to hurt..." He tilted his head up to kiss Loki's chin, trying to show that he didn't mind the ache so much, and held on a little more securely to the Mer's shoulders, a soft, breathy, "And maybe some more of your pretty fingers on my cock wouldn't go amiss..."   
  
Loki wrapped an arm around Tony's form, pulling him closer so that he could slide into the deeper waters with ease. With a powerful flick of his tail the Mer pulled them both back to his nest, bodies twisting and turning until he lay back against the pelts that lined the floor. With Tony now situated on  _ top _ of him Loki couldn’t help but chuckle, a hand slipping between them to curl around Tony's hardening cock. "Is this better?" He purred, tail giving a lazy roll, his shaft giving a rough twitch and a thick spurt of cum.   
  
Tony hissed as Loki's fingers curled around him, but he quickly relaxed beneath his hands. He pressed his lips to Loki's chin as the Mer thrust lazily into him, a soft groan slipping out. His brows furrowed as a fresh spurt of Loki's seed filled him further, his stomach distending and stretching with it.   
  
He swallowed hard and whimpered, one of his hands reaching out to grab hold of Loki's shoulders. His fingers slid down the length of the Mer's arms until they circled his wrists so that Tony could pull Loki's hands to cup his belly. "Need you to," he murmured sheepishly, holding Loki's hands tightly over his stomach, his eyes squeezing shut.   
  
Splaying those long, elegant fingers against his lover's stomach, he grinned, teeth flashing before he spoke. "Need me to do what, my love?" Rolling his tail, he tested their connection, that pesky knot of his still holding firm. "You know how long we can be stuck like this... It could still be a few moments more." Gently raking his nails down Tony's stomach, Loki took him up again to give his cock a few quick strokes.   
  
"You look so  _ full, _ " Loki crooned, his free hand stroking over his distended stomach. "So beautiful... You take me so well. Even now I can feel you clinging to me so sweetly.  _ Norns.. _ ."   
  
"Just this," Tony murmured softly, fingers clutching tightly to Loki's hand, encouraging the gentle stroking over his belly, the other reaching back to hold the Mer's hip to guide his lazy thrusts, "Just this." He whimpered softly and rocked back against his lover, clenching his hole tight around Loki's prick and milking his knot to the best of his ability.   
  
Loki's hand moved over Tony's cock, matching the lazy pace of his thrusts. Limited by how much he could move, the Mer didn’t seem to mind, instead settling for churning his hips and flexing his tail. Grinding his flexible member as deep as it would go, stirring up the seed that filled his lover's hole, while pumping him full of even  _ more. _ "Gods, look at you... I can only imagine how well you would take my eggs... It's a shame I can't give them to you." But hey, that didn't keep him from dreaming, right?   
  
A sharp intake of breath, hissed through his teeth, was the only sound Tony could muster as he spilled over his lover's fingers. The thought of being filled up by his lover's eggs, of potentially carrying their unborn children, was something that never ceased to turn the engineer on. That triggered the memory of a conversation they'd once had…   
  
_ "So, if Thor can just ditch his tail, does that mean...?” _   
  
"Couldn't you," Tony gasped, breathless and lust-drunk, exhausted from their love-making and, as far as he was concerned, never more serious in his life, "If Thor can... then couldn't we...?"   
  
A pleased shudder rolled through him, the taste of Tony's seed on his tongue and filling his senses ushering forth a low groan. Flexing his fingers, the Mer rolled them over, nose burying into the crook of his lover’s neck. "What do you mean, my love?" He asked, pulling back to peek through the dark curtain of his hair to look down at Tony's face. Soothing his palms over his human’s hips, Loki rolled onto his side, curling close against him. "Use your words~"   
  
"I'm ready," Tony breathed, tucking his face into the crook of Loki's shoulder to whisper in his ear, his fingers holding tight to the Mer's shoulders. He closed his eyes and nuzzled Loki's cheek, his lips brushing the lobe of the Mer's ear, "I've already dedicated everything that I am to you, Loki. What's this one last thing in the long run?"   
  
He shook his head and swallowed hard, quickly realizing he was making little sense, "When Thor chose Jane, you said that he could be with her for the rest of his days if he wanted to. So, the big lug ditched his tail to be with her on land."   
  
Tony worried his lip between his teeth for a long moment, then peered up at his lover, fingers stroking up the line of his throat to cradle his head between his hands, "I choose  _ you, _ Loki. I have since the day we met." He tilted his head up further and pressed his lips chastely to Loki's, "I want to live the rest of my life with you. Down here, where you call home. I don't want to take you from everything you love. I want to be part of it. I want to stay with you."   
  
Loki went still, pulling away with a blink to cast a baffled look down at his companion. Furrowing his brow, he smiled nervously, chin dipping so that he could brush his lips along Tony's forehead. "You would give up your legs...your  _ life _ above ground, and all that comes with it,  _ just _ to be with me?" Finned ears gave a twitch, head tilting as he gazed lovingly into those big brown eyes.   
  
"You would never be able to return above ground... Nor see your loved ones, or your friends, unless they came here." Loki ran a hand down along Tony's hip and thigh, his head dipping so that he could follow his touch with his eyes. "It may be painful for a mortal to go through the change. With your heart as fragile as it is..." Placing a palm over Tony's arc reactor, he frowned and looked him in the eyes. "I am unsure if your body can handle it..."   
  
"Babe, everyone that gives a shit about me already knows that  _ my life is down here _ ," Tony gave Loki a small, wane smile and clung just a bit tighter to him, "Honestly, Rhodes is surprised that I even bother coming back at all. As for my body, well..."   
  
His nose twitched and he swallowed with some effort, his throat bobbing visibly as his gaze flicked away, then back, "You like to tease that I'm going gray, but I  _ am _ getting older, Lokes, and I'm not sure how many more trips I'm going to be able to make. The compression and decompression process is hard on a  _ young, healthy body _ ..."   
  
He cleared his throat and brought his big brown eyes back to Loki's soft silvery blue, "If I'm going to do this, then why not now...?  _ Hell _ , I should have done it  _ the day _ you and Thor figured out you could!" He gently brushed inky locks behind Loki's finned ear, despite the futility of the habit, and gave him a sheepish little smile as he whispered, "I want a  _ family _ with you, Lokes. Our own little tadpoles, or-or  _ spawn _ , _ or whatever you'd call them _ ... But the point being..."   
  
He touched his nose to Loki's, never more aware of their bodies linked so blissfully, impossibly  _ close _ , "I don't want you to have to keep dreaming about us being together. I want to make that a  _ reality _ ."   
  
A loving croon poured from the Mer's throat, his arms wrapping around his lover's body, holding him tight as he nuzzled into his hair. Around him he let his fins flare, shimmering and shining in the light around them. "You know not how long I've wanted to hear this... How long I've  _ dreamt _ of having you in my arms every night of every day."   
  
Loki brushed his lips along the marks he'd left on Tony's neck. Over the fresh, pink scars that would soon blend in with those he had left over the years. "If you are ready for this, then so am I. But I must know... I  _ must _ know that you will not shy away from this." Grabbing at Tony's upper arms, he gave him a small shake. "There is no going back, Anthony. There is no 'undoing' what will be done."   
  
"I mean, Jane has the lecture circuit down, Rhodes has been running the marine corps side of things since day one, Pep may as well run SI already, and the rest of the team already live here full time anyway," he babbled excitedly, his hands fluttering between them as he spoke, his eyes bright and happy.   
  
"Hell! J," Tony called, his eyes never leaving the Mer before him.   
  
_ "How might I be of service, sir?" _   
  
"Initiate 'Part of Your World' protocol," Tony grinned wide even as he said it, knowing the name was cheesy, but that Loki would be able to appreciate the pun. You couldn't be a real life merman, have an eccentric, nerdy billionaire as your boyfriend, and  _ not _ see the 'Little Mermaid'.   
  
_ "Initiating 'Part of Your World' protocol. Authorization required, sir." _   
  
Tony looked meaningfully at Loki, his smile dimming around the edges and his mannerisms serious, "I've thought about this almost constantly since we met, Lokes." He brought his hands to rest on the Mer's cheeks and pressed their foreheads together, "I set all of this up as soon as I got back from..." He tapped the reactor meaningfully and nibbled at his lip worriedly, then let out a breath that left him trembling with adrenaline and nerves, "I dedicated my whole life to finding you when I got back and I don't want to ever have to go without you again..."   
  
"If push comes to shove I  _ suppose _ I could teach you how to form legs again..." The Mer purred, nuzzling their noises together with a sheepish smile. "After a few decades of having you all to myself, of course." The world above had his beloved Anthony for far too long. Now that they had the opportunity to spend their lives together? Who knew all of the new and exciting things that were bound to happen?   
  
Pressing a chaste kiss to Tony's lips, the Mer gave a flick of his tail, rolling his lover's body on top of him, much like he had before. Lifting him up by the hips, Loki carefully eased his softening cock free with a groan, his cheeks tinting pink. "The transformation may take some time, but it will also be easier with a part of me already inside of you." Splaying a hand over Tony's distended belly, he flashed a shark-like grin. "You don't know how eager I am for what's to come.”   
  
"You just want to knock me up," Tony chuckled and licked his lips nervously, a habit he was certain he'd never break, then glanced up towards the ceiling for a moment, though his gaze quickly returned to his lover, "Authorization code '1-2-1-7-0-8'."   
  
_ "Authorization Code Accepted. 'Part of Your World' protocol has been initiated. Congratulations, sir. Please keep in touch." _   
  
"You got it, J," Tony murmured and leaned in to press his lips to Loki's, his fingers tangling in his hair as the doors and view ports of their cabin silently closed over, leaving only the tunnel out into the open ocean still accessible.   
  
Tony smiled as he pulled back for a moment, tongue lapping over his lips to taste his lover, "Let's do this..."

"On the contrary, I want you to knock  _ me _ up." Loki nipped at Tony's lips and pulled back, a strong arm curling about the mortal's form to anchor him close. With a flick of his tail he carried them toward the hatch that led outside, the lights growing dim around them. "Come, let me show you what awaits us in this new life."

**Author's Note:**

> Please let us know what you think and if you'd like to possibly see more from this universe. No promises, of course, but we would love to hear what you guys think~! <3


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